P2246

P2246-O2 SENSOR 1/1, 2/1 REFERENCE VOLTAGE CIRCUIT HIGH

For a complete wiring diagram, refer to the Wiring Information.

Theory of operation
The Oxygen sensors (O2 sensor) are used for fuel control and catalyst monitoring. Each O2 sensor compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the Powertrain Control Module (PCM) operates in an Open Loop mode, ignoring the O2 sensor signal voltage while calculating the air-to-fuel ratio. The heating elements inside each O2 sensor heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the PCM to calculate the air-to-fuel ratio sooner. While the engine runs, the O2 sensor heats up and begins to generate a voltage within a range of 0-1,275 mV. Once sufficient O2 sensor voltage fluctuation is observed by the PCM, Closed Loop is entered. The PCM uses the O2 sensor voltage to determine the air-to-fuel ratio. An O2 sensor voltage that increases toward 1,000 mV indicates a rich fuel mixture. An O2 sensor voltage that decreases toward 0 mV indicates a lean fuel mixture.
- When Monitored:
Continuously after 15 seconds of engine runtime, no O2 sensor heater DTCs present and battery voltage greater than 10.4 Volts.

- Set Condition:
The Oxygen Sensor reference voltage is below 0.9 of a Volt for 60 seconds. The DTC will set as Pending after one trip and Active after two trips. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: The most likely cause of this DTC is O2 Return circuit shorted to voltage.

1. Ignition on, engine not running.
2. With the scan tool, select View DTCs. Copy DTC and Freeze Frame information.
3. Start the engine.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

4. Allow the engine to reach normal operating temperature.
5. Monitor the scan tool for at least two minutes.
6. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. O2 RETURN CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the C1 and C2 PCM harness connectors.
3. Disconnect the 1/1 O2 Sensor harness connector.
4. Disconnect the 1/2 O2 Sensor harness connector.
5. Turn the ignition on.
6. Measure the voltage on the O2 Return circuit at the O2 Sensor 1/1 and 1/2 harness connectors.

Is there any voltage present?

Yes

- Repair the O2 Return circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. 1/1 OR 1/2 O2 SENSOR




1. Turn the ignition off.
2. Connect the C1 and C2 PCM harness connectors.
3. Ignition on, engine not running.
4. With the scan tool, monitor the 1/1 and 1/2 O2 Sensor voltage.
5. Connect a jumper wire between the O2 Signal 1/1 circuit and the O2 Return circuit in the O2 Sensor harness connector.
6. Repeat step 5 for the O2 Sensor 1/2 Signal circuit

Is the voltage between 2.3 and 2.7 Volts with the jumper wire installed?

Yes

- Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module connectors. Replace the O2 Sensor not indicating the specified voltage if no problems were found with the connections. Oxygen Sensor - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4
NOTE: Remove the jumper wire before continuing.


4. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oxygen Sensors and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.